Rotating electric machine

ABSTRACT

An automotive alternator in which a fan rotating together with a rotor to direct air from a suction aperture into a case, blow the air centrifugally, and discharge the air externally through a discharge aperture has a blade including an interposed portion extending axially from an end surface of a pole core between an adjacent pair of claw-shaped magnetic poles. For this reason, cooling of a rotor coil and a stator coil is improved by improving capacity of the fan in a limited space, thereby enabling output to be improved.

TECHNICAL FIELD

The present invention relates to a dynamoelectric machine in which a fanis mounted to an end surface of a Lundell rotor.

BACKGROUND ART

In automotive alternators using a Lundell rotor mounted with fans,cooling airflows are generated centrifugally by the fans together withrotation of the rotor to cool stator coil ends, brackets transmittingstator heat, etc. A rectifier and a regulator are also cooled by coolingairflows sucked in by the fans. Since these cooled bodies each have aheat resistance limit, if cooling is not achieved sufficiently, forexample, the heat resistance limit may be exceeded, causing damage, andif that is to be prevented, it may be necessary to reduce flowingelectric current values. In other words, electric current generated inthe alternator must be suppressed, reducing output performance.

In environments surrounding automotive alternators, there has been atendency in recent years for thermal environments to be high intemperature and severe due to factors such as rising ambienttemperatures in engine compartments, increases in onboard electricalequipment, etc., accompanying reductions in engine compartment size, andhigh-density arrangement of peripheral parts in engine compartments,etc.

In addition, in order to meet demands for compact size, light weight,and high output that are sought in automotive alternators, automotivealternators show a tendency toward size reduction, which leads toreductions in cooling fan diameters, but there is a possibility thatthis may be accompanied by deterioration in automotive alternatorcooling due to reductions in cooling airflow rate, and there is anurgent need to achieve improvements in automotive dynamoelectric coolingto overcome these problems.

In answer to demands of this kind, alternators are known in whichcooling efficiency is improved by combining a front-end cooling fanhaving oblique-flow blades and a rear-end cooling fan having centrifugalblades, fixing the rear-end cooling fan to an end surface of a Lundellpole core away from a pulley, fixing the front-end cooling fan to an endsurface of the pole core near the pulley, and selecting oblique-flowblades having an optimal shape (See Patent Literature 1, for example).

Patent Literature 1

Japanese Patent Laid-Open No. HEI 09-154256 (Gazette)

However, In an automotive alternator of the above configuration,settings are required that place importance on better cooling inresponse to increases in the amount of heat generated by electricalcomponents such as three-phase stator coils, rotor coils, etc., in orderto adapt to compact size and high output, but cooling airflow ratecannot be made to catch up merely by optimizing the shape of theoblique-flow blades of the front-end cooling fan, and means forincreasing the airflow rate must inevitably be considered.

Conceivable examples of means for improving the cooling airflow rateinclude increasing the number of oblique-flow blades in the cooling fan,and increasing the area of the oblique-flow blades, etc., but inmanufacturing methods involving press-forming ferrous metal plates,etc., since a plurality of oblique-flow blades are cut and raise from asingle sheet of generally disk-shaped base material, increasing thenumber of blades and increasing the area of the blades conflict witheach other, and one problem has been that normally the number of bladesand the area of the blades must be selected by making a certain tradeoff, making it extremely difficult to achieve both improvements inoutput and reductions in size in automotive alternators.

DISCLOSURE OF INVENTION

The present invention aims to solve the above problems and an object ofthe present invention is to provide a dynamoelectric machine enablingoutput to be improved by improving capacity of a fan in a limited spaceso as to improve cooling of a rotor coil and a stator coil.

In order to achieve the above object, according to one aspect of thepresent invention, there is provided a dynamoelectric machine in which afan rotating together with a rotor to direct air from a suction apertureinto a case, blow the air centrifugally, and discharge the airexternally through a discharge aperture has a blade including aninterposed portion extending axially from an end surface of a pole corebetween an adjacent pair of claw-shaped magnetic poles.

Using a dynamoelectric machine according to the present invention,cooling of a rotor coil and a stator coil is improved by improvingcapacity of the fan in a limited space, thereby enabling output to beimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section showing an automotive alternator according toEmbodiment 1 of the present invention;

FIG. 2 is a partial enlargement of rear-end coil ends from FIG. 1;

FIG. 3 is a side elevation showing a rear-end fan from FIG. 1;

FIG. 4 is a front elevation showing the rear-end fan from FIG. 1 whenviewed from a rear bracket side;

FIG. 5 is a developed projection of the rear-end fan from FIG. 1 beforeshaping;

FIG. 6 is a side elevation showing a rear-end fan of an automotivealternator according to Embodiment 2 ;

FIG. 7 is a front elevation showing the rear-end fan from FIG. 6 whenviewed from a rear bracket side;

FIG. 8 is a developed projection of the rear-end fan from FIG. 6 beforeshaping;

FIG. 9 is a side elevation showing a rear-end fan of an automotivealternator according to Embodiment 3;

FIG. 10 is a front elevation showing the rear-end fan from FIG. 9 whenviewed from a rear bracket side;

FIG. 11 is a developed projection of the rear-end fan from FIG. 9 beforeshaping;

FIG. 12 is a side elevation showing a rear-end fan of an automotivealternator according to Embodiment 4 ; and

FIG. 13 is a front elevation showing the rear-end fan from FIG. 12 whenviewed from a rear bracket side.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be explainedbased on drawings, and identical or corresponding members and portionsin the drawings will be given identical numbering.

Embodiment 1

FIG. 1 is a cross section showing an automotive alternator according toEmbodiment 1 of the present invention.

In an automotive alternator constituting a dynamoelectric machine, ashaft 5 having a pulley 4 fixed to a first end portion is rotatablydisposed inside a case 3 constituted by a front bracket 1 and a rearbracket 2 made of aluminum. A Lundell rotor 6 is fixed to the shaft 5. Afront-end fan 7 is fixed to a front-end end surface of the rotor 6 nearthe pulley 4, and a rear-end fan 8 is fixed to a rear-end end surfaceaway from the pulley 4. A stator 9 is fixed to an inner wall surface ofthe case 3 in a vicinity of the rotor 6 so as to surround the rotor 6.

Slip rings 10 for supplying electric current to the rotor 6 are fixed toa second end portion of the shaft 5. A pair of brushes 11 housed insidea brush holder 12 slide in contact with surfaces of the slip rings 10. Aregulator 13 for adjusting magnitude of alternating voltage generated inthe stator 9 is fixed to the brush holder 12. A rectifier 14electrically connected to the stator 9 so as to convert alternatingcurrent into direct current is also disposed inside the rear bracket 2.

A plurality of front-end suction apertures 1 a are formed on aradially-inner side of the front bracket 1 and a plurality of front-enddischarge apertures 1 b are formed on a radially-outer side. A pluralityof rear-end suction apertures 2 a are formed on a radially-inner side ofthe rear bracket 2, and a plurality of rear-end discharge apertures 2 bare formed on a radially-outer side.

The above rotor 6 includes: a rotor coil 15 for generating magnetic fluxon passage of electric current; and a pole core disposed so as to coverthe rotor coil 15. The pole core includes a front-end pole core body 16and a rear-end pole core body 17 magnetized into North-seeking (N) polesand South-seeking (S) poles by the magnetic flux. The front-end polecore body 16 and the rear-end pole core body 17 have front-endclaw-shaped magnetic poles 18 and rear-end claw-shaped magnetic poles19, respectively, that are claw-shaped and intermesh with each other.The number of front-end claw-shaped magnetic poles 18 and rear-endclaw-shaped magnetic poles 19 is eight each.

The stator 9 includes: a stator core 20 through which a rotatingmagnetic field from the rotor 6 passes; and a stator coil 21 disposedradially inside the stator core 20. A plurality of slots formed so as toextend axially are disposed at a uniform pitch around an entirecircumference radially inside the stator core 20, which is configured bystacking steel sheets.

The stator coil 21 is configured by winding conducting wirescontinuously into distributed windings so as to be folded over outsidethe slots at first and second end surfaces of the stator core 20 to formfront-end coil ends 22 and rear-end coil ends 23 and alternately occupyan inner layer and an outer layer in a slot depth direction inside theslots at intervals of a predetermined number of slots.

An axial length of the stator core 20 is shorter than an axial length ofthe pole core.

FIG. 2 is a partial enlargement of the rear-end coil ends 23.

Each of the conducting wires constituting the rear-end coil ends 23 isconstituted by: straight portions 24 projecting straight outward(axially) from a rear-end end surface of the stator core 20; andcrossover portions 25 bent radially and circumferentially, and a space δis formed above the rear-end end surface of the stator core 20.

Moreover, the front-end coil ends 22 also have a configuration similarto that of the rear-end coil ends 23, and a space δ is also formed abovethe front-end end surface of the stator core 20.

FIG. 3 is a side elevation showing the rear-end fan 8 shown in FIG. 1,and FIG. 4 is a front elevation showing the rear-end fan 8 from FIG. 1when viewed from a rear bracket 2 side.

The rear-end fan 8 is constituted by: a base 30 fixed to the rear-endend surface of the rotor 6; and a plurality of blades 31 disposed so asto extend perpendicular to the base 30. Each of the blades 31 isconstituted by: a root portion 32 extending away from the front-end polecore body 16 from an end surface of the rear-end pole core body 17; anda generally triangular interposed portion 33 extending between anadjacent pair of rear-end claw-shaped magnetic poles 19 and 19 andhaving a truncated leading end.

FIG. 5 is a developed projection of the above rear-end fan 8 beforeshaping. The rear-end fan 8 is formed by punching a flat plateconstituted by a nonmagnetic material into the shape shown in FIG. 5 andthen bending it at 90 degrees at positions indicated by broken lines αin FIG. 5.

Moreover, the front-end fan 7 also has a construction identical to thatof the rear-end fan 8, and explanation thereof will be omitted.

In an automotive alternator having the above configuration, electriccurrent is supplied from a battery (not shown) through the brushes 11and the slip rings 10 to the rotor coil 15, generating a magnetic fluxand giving rise to North-seeking (N) poles and South-seeking (S) polesin the front-end and rear-end claw-shaped magnetic poles 18 and 19,respectively.

At the same time, since the pulley 4 is driven by an engine and therotor 6 is rotated by the shaft 5, a rotating magnetic field is appliedto the stator core 20, giving rise to electromotive force in the statorcoil 21.

This alternating-current electromotive force passes through therectifier 14 and is converted into direct current, magnitude thereof isadjusted by the regulator 13, and the battery is charged.

The front-end fan 7 also rotates due to the rotation of the rotor 6, anddue to the rotation of the fan 7, air enters through the front-endsuction apertures 1 a in the front bracket 1, cools the front-end coilends 22 of the stator coil 21, etc., and is discharged through thefront-end discharge apertures 1 b, as indicated by arrow A in FIG. 1.

In the front-end fan 7, because the interposed portions of the bladesare disposed axially between the pairs of front-end claw-shaped magneticpoles 18 and 18, air between the front-end claw-shaped magnetic poles 18and 18 is also swept out centrifugally, and that air is also dischargedexternally through the front-end discharge apertures 1 b, as indicatedby arrows B in FIG. 1.

The rear-end fan 8 also rotates due to the rotation of the rotor 6, anddue to the rotation of the fan 8, air enters through the rear-endsuction apertures 2 a in the rear bracket 2, cools the rectifier 14, theregulator 13, and the rear-end coil ends 23 of the stator coil 21, etc.,and is discharged through the rear-end discharge apertures 2 b, asindicated by arrows C in FIG. 1.

In the rear-end fan 8, because the interposed portions 33 of the blades31 are disposed axially between the pairs of rear-end claw-shapedmagnetic poles 19 and 19, air between the rear-end claw-shaped magneticpoles 19 and 19 is also swept out centrifugally, as indicated by arrowsD in FIG. 1, and that air is also discharged externally through therear-end discharge apertures 2 b.

In an automotive alternator of the above configuration, because theinterposed portions on the blades of the front-end fan 7 are disposed soas to extend between the front-end claw-shaped magnetic poles 18 and 18,the area of the blades is increased and air between the front-endclaw-shaped magnetic poles 18 and 18 also flows centrifugally togetherwith rotation of the rotor 6, and as a result, the flow of air overouter peripheral surfaces of the rotor coil 15 becomes active, improvingthe cooling performance of the rotor coil 15 proportionately. For thisreason, the amount of the electric current flowing through the rotorcoil 15 can be increased, increasing output current values generated bythe stator 9.

Because the interposed portions 33 on the blades 31 of the rear-end fan8 are disposed so as to extend between the rear-end claw-shaped magneticpoles 19 and 19, the area of the blades 31 is increased and air betweenthe rear-end claw-shaped magnetic poles 19 and 19 also flowscentrifugally together with rotation of the rotor 6, and as a result,the flow of air over outer peripheral surfaces of the rotor coil 15becomes active, improving the cooling performance of the rotor coil 15proportionately. For this reason, the amount of the electric currentflowing through the rotor coil 15 can be increased, increasing outputcurrent values generated by the stator 9.

Because straight portions 24 projecting straight outward (axially) fromend surfaces of the stator core 20 are disposed on each of theconducting wires in the front-end coil ends 22 and the rear-end coilends 23, a space δ is formed above the end surface of the stator core20, reducing air resistance in the coil ends 22 and 23, and increasingthe flow rate of air passing through the coil ends 22 and 23.Consequently, radiating characteristics of the stator coil 21 areimproved.

Because the blades of the front-end fan 7 and the blades 31 of therear-end fan 8 are constituted by a nonmagnetic material, magnetic fluxis prevented by means of the interposed portions 33 from leaking outanywhere between front-end and rear-end claw-shaped magnetic poles 18and 19 having opposite poles.

Because the stator coil 21 is configured by winding conducting wiresinto distributed windings disposed in an orderly manner inside the slotsat intervals of a predetermined number of slots, the overall length ofthe conducting wires can be shortened, reducing electrical resistance ofthe stator coil 21 proportionately, and enabling output current to beincreased.

Because the fans 7 and 8 are formed by bending flat plates, they can bemanufactured simply.

Embodiment 2

FIG. 6 is a side elevation showing a rear-end fan 40 of an automotivealternator according to Embodiment 2 of the present invention, and FIG.7 is a front elevation showing the rear-end fan 40 from FIG. 6 whenviewed from a rear bracket 2.

In this embodiment, a rear-end fan 40 is constituted by: a base 41 fixedto an end surface of a rear-end pole core body 17; and a plurality ofblades 42 disposed so as to extend so as to be inclined relative to thebase 41. Each of the blades 42 is constituted by: a root portion 43disposed so as to extend from the base 41; and a generally triangularinterposed portion 44 extending between an adjacent pair of rear-endclaw-shaped magnetic poles 19 and 19 from the root portion 43 and havinga truncated leading end.

FIG. 8 is a developed projection of the above rear-end fan 40 beforeshaping. The rear-end fan 40 is formed by punching a flat plateconstituted by a nonmagnetic material into the shape shown in FIG. 8 andthen bending it at acute angles out from the surface of the page atpositions indicated by broken lines a in FIG. 8.

Moreover, a front-end fan also has a construction identical to that ofthe rear-end fan 40, and explanation thereof will be omitted.

The rest of the configuration is similar to that of Embodiment 1.

In an automotive alternator according to Embodiment 2, because theinterposed portions 44 of the blades 42 of the rear-end fan 40 projectbetween pairs of the rear-end claw-shaped magnetic poles 19 and 19toward one of the rear-end claw-shaped magnetic poles 19 and 19, air atan end surface of the rotor 6 flows axially, that is, is led between therear-end claw-shaped magnetic poles 19 and 19 intentionally, making theflow of air over outer peripheral surfaces of the rotor coil 15 active,thereby improving the cooling performance of the rotor coil 15proportionately more than that of Embodiment 1.

Moreover, because the front-end fan also has effects identical to thoseof the rear-end fan 40, explanation thereof will be omitted.

Embodiment 3

FIG. 9 is a side elevation showing a rear-end fan 50 of an automotivealternator according to Embodiment 3 of the present invention, and FIG.10 is a front elevation showing the rear-end fan 50 from FIG. 9 whenviewed from a rear bracket 2.

In this embodiment, a rear-end fan 50 is constituted by: a base 51 fixedto an end surface of a rear-end pole core body 17; and a plurality ofblades 52 disposed at a uniform pitch circumferentially around the base51. Each of the blades 52 is constituted by: a root portion 53 disposedso as to extend from the base 51; and a generally triangular interposedportion 54 extending between an adjacent pair of rear-end claw-shapedmagnetic poles 19 and 19 from the root portion 53 and having a truncatedleading end. The interposed portions 54 are bent at a bent portion 55 atan intermediate portion so as to have an angular shape. Spaces 6 aboveend surfaces of a stator core 20 are disposed radially outside the bentportions 55.

FIG. 11 is a developed projection of the above rear-end fan 50 beforeshaping. The rear-end fan 50 is formed by punching a flat plateconstituted by a nonmagnetic material into the shape shown in FIG. 11,bending it at acute angles out from the surface of the page at positionsindicated by broken lines a in FIG. 11, and then bending it in towardthe surface of the page at the bent portions 55 of the interposedportions 54.

Moreover, a front-end fan also has a construction identical to that ofthe rear-end fan 50, and explanation thereof will be omitted.

The rest of the configuration is similar to that of Embodiment 1.

In an automotive alternator according to Embodiment 3, because theblades 52 of the rear-end fan 50 are bent so as to have an angularshape, when air from the direction of arrow I in FIG. 9 contacts theblades 52 together with rotation of the rotor 6, much of the air isgathered into the bent portions 55 and advances centrifugally so as topass through the spaces δ above the end surface of the stator core 20and be discharged externally through the rear-end discharge apertures 2b. Consequently, the flow rate of air passing through the coil ends 23increases, improving the radiating characteristics of the stator coil 21in particular.

Moreover, because the front-end fan also has effects identical to thoseof the rear-end fan 50, explanation thereof will be omitted.

Embodiment 4

FIG. 12 is a side elevation showing a rear-end fan 60 of an automotivealternator according to Embodiment 4 of the present invention, and FIG.13 is a front elevation showing the rear-end fan 60 from FIG. 12 whenviewed from a rear bracket 2.

In an automotive alternator according to Embodiment 4, first and secondblades 61 and 62 are disposed at a nonuniform pitch circumferentially,the first blades 61, which are positioned between pairs of rear-endclaw-shaped magnetic poles 19, have a similar shape to that of theblades 31 according to Embodiment 1, and the second blades 62, which arenot positioned between pairs of rear-end claw-shaped magnetic poles 19,in other words, which face the rear-end claw-shaped magnetic poles 19,are rectangular blades.

Moreover, a front-end fan also has a construction identical to that ofthe rear-end fan 60, and explanation thereof will be omitted.

The rest of the configuration is similar to that of Embodiment 1.

In an automotive alternator having the above configuration, because theblades 61 and 62 are disposed at a nonuniform pitch circumferentially,vibrational effects are suppressed, reducing noise occurring due to therotation of the rear-end fan 60. Because the interposed portions on thefirst blades 61 of the rear-end fan 60 are disposed so as to extendbetween pairs of rear-end claw-shaped magnetic poles 19 and 19, airbetween the rear-end claw-shaped magnetic poles 19 and 19 also flowscentrifugally together with rotation of the rotor 6, and as a result,the flow of air over outer peripheral surfaces of the rotor coil 15becomes active, improving the cooling performance of the rotor coil 15proportionately.

Moreover, because the front-end fan also has effects identical to thoseof the rear-end fan 60, explanation thereof will be omitted.

Moreover, in each of the above embodiments, explanations have been givenfor automotive alternators, but the present invention can also beapplied to other alternating-current generators driven to rotate usingan internal combustion engine other than a vehicle-mounted engine, or anelectric motor, a water wheel, etc., as a driving source.

The present invention can also be applied to any electric motorconstituting a dynamoelectric machine in which a rotor is rotated bypassing electric current to a stator coil to generate a rotatingmagnetic field in the stator coil.

In each of the above embodiments, the fans 7, 8, 40, 50, and 60 areconstituted by a non-magnetic material, but of course the fans may alsobe made of iron.

In that case, because the blades are constituted by a magnetic material,there is a risk that magnetic flux may flow through the. interposedportions anywhere between opposite claw-shaped magnetic poles. In answerto this, such magnetic flux leakage can be prevented by settingdistances between the interposed portions and adjacent claw-shapedmagnetic poles so as to be greater than a distance between an innerperipheral surface of the stator core and an outer peripheral surface ofthe rotor.

Heat-generating members can be cooled more effectively by fixing a fanhaving interposed portions only to an end surface of a pole core near arectifier.

In each of the above embodiments, cases in which fans 7, 8, 40, 50, and60 were fixed to end surfaces of a pole core have been explained, but afan needs only to rotate together with a rotor, and may also be fixed toa shaft, for example.

1-11. (canceled)
 12. A dynamoelectric machine comprising: a case havinga suction aperture for sucking in air and a discharge aperture fordischarging said air; a rotor including: a rotor coil disposed so as tobe fixed to a shaft inside said case, said rotor coil generatingmagnetic flux on passage of electric current; and a Lundell pole coredisposed so as to cover said rotor coil, said pole core having aplurality of claw-shaped magnetic poles that are magnetized by saidmagnetic flux; a stator including: a stator core disposed so as tosurround said rotor; and a stator coil formed by winding a conductingwire into slots extending axially on said stator core; a fan rotatingtogether with said rotor, said fan directing said air from said suctionaperture into said case, blowing said air centrifugally, and dischargingsaid air externally through said discharge aperture, said pole corebeing constituted by a first pole core body and a second pole core bodyin which said claw-shaped magnetic poles intermesh with each otheralternately, wherein: said fan has a blade including an interposedportion extending axially from an end surface of said pole core betweenan adjacent pair of said claw-shaped magnetic poles.
 13. Thedynamoelectric machine according to claim 12, wherein: said stator coilis wound into a distributed winding in which said conducting wire isdisposed in a orderly manner inside said slots at intervals of apredetermined number of slots.
 14. The dynamoelectric machine accordingto claim 12, wherein: a coil end is formed in said stator coil byfolding said conducting wire over outside an end surface of said statorcore; and a space is formed in said coil end above said end surface bysaid conducting wire having straight portions projecting axially outwardfrom said end surface.
 15. The dynamoelectric machine according to claim12, wherein: said interposed portion of said blade projects toward oneof said claw-shaped magnetic poles in said adjacent pair of claw-shapedmagnetic poles.
 16. The dynamoelectric machine according to claim 12,wherein: said interposed portion of said blade is bent at a bent portionso as to have an angular shape when viewed radially.
 17. Thedynamoelectric machine according to claim 14, wherein: said interposedportion of said blade is bent at a bent portion so as to have an angularshape when viewed radially; and said bent portion is disposed radiallyopposite said space.
 18. The dynamoelectric machine according to claim12, wherein: said fan is formed by bending a flat plate.
 19. Thedynamoelectric machine according to claim 12, wherein: said fan is madeof iron; and a distance between said interposed portion and saidadjacent pair of claw-shaped magnetic poles is greater than a distancebetween an inner peripheral surface of said stator core and an outerperipheral surface of said rotor.
 20. The dynamoelectric machineaccording to claim 12, wherein: said fan is constituted by a nonmagneticmaterial.
 21. The dynamoelectric machine according to claim 12, wherein:blades of said fan are disposed at a nonuniform pitch circumferentially;and a blade disposed between an adjacent pair of said claw-shapedmagnetic poles has said interposed portion.
 22. The dynamoelectricmachine according to claim 12, wherein: said fan is fixed only to an endsurface of said pole core near a rectifier for converting alternatingcurrent generated in said stator into direct current.